The Core embodies four areas of expertise: Quantitative Methods and Biostatistics; Qualitative Methods and Ethnography; Operations Research and Mathematical Modeling; and Biological Measures and Analysis. Dr. Trace Kershaw, Core Director, is a behavioral scientist and Associate Professor at Yale School of Public Health with over 12 years of experience conducting HIV behavioral and intervention studies domestically and internationally.' Dr. Kershaw has expertise in using technology-based assessments (e.g. ACASI, web-based, hand held devices, cell phones), complex designs (e.g. longitudinal, clustered, randomized controlled trials, mixed methods), and advanced analytic techniques (e.g. multilevel modeling, dyadic data analysis, structural equation modeling, latent growth curves, latent class analysis, recursive partitioning). Dr Kershaw has served as the lead methodologist on several CIRA-affiliated studies including Dr. Ickovics' implementation study of her HIV prevention intervention for pregnant women in community clinics in New York. This breadth of expertise makes Dr. Kershaw well qualified to lead the Core's expanding focus on implementation science. Dr Kershaw will oversee all aspects of the Core's activities including chairing Core meetings, working in close coordination with Core scientists, and implementing and overseeing Core policies and procedures to ensure they are appropriate and efficient. In addition to Dr. Kershaw, the Core will be led by two Co-Directors with expertise essential to the functioning of the Core. Dr. Jean Schensul is founder of and Senior Scientist at The Institute for Community Research and an internationally known medical anthropologist with over 25 years of experience in the conduct of community-based HIV interventions.^''^ She has expertise in qualitative and mixed methods research and is the author of an acclaimed seven book series on ethnographic methods that is currently being revised for a 2nd Edition. Dr. Scott Braithwaite, Associate Professor of Internal Medicine at New York University, is an expert in operations research, decision science, mathematical modeling, and cost and quality effectiveness analysis. His mathematical models of HIV disease progression are known to be among the most comprehensive and sophisticated available for exploring HIV clinical interventions. The Co- Directors will help Dr Kershaw plan the Core direction and activities, lead the development of training activities, and oversee consultations. Dr Russell Barbour will serve as the Associate Director and will be in charge of the day to day functioning of the Core, organize Core activities, provide data analysis and consultation services, and oversee Core evaluation and monitoring. Dr. Barbour is a statistician trained in ecological studies with expertise in multivariate and longitudinal statistics, spatial statistics, neural networks, and advanced sampling techniques. Other contributing Core scientists (Figure BI) will participate in Core activities including seminars, consultations, and meetings. All Core scientists will be positioned across four areas of expertise: